Plant species diversity is fundamental for the stability and resilience of ecosystems, and the well-being of the entire planet. Healthy and diverse ecosystems also contribute to air and water pollution removal, climate regulation and flood prevention. In the last century, plant biodiversity has been facing severe threats, such as habitat destruction and fragmentation due to increasing urbanization, deforestation, agricultural expansion, wildfires, and pollution. In addition, changes in climate pose significant threats to plants biodiversity conservation and native species preservation. All these natural and anthropic disturbance factors are profoundly modifying the competitive dynamics among plant species, often favouring the establishment and spread of some invasive plants, and exacerbating the biodiversity loss of native ecosystems.

A well-known invasive alien species is Ailanthus altissima, a tree native to East Asia and introduced to various regions around the world, including North America and Europe. It is characterized by rapid growth, high reproductive capacity, and ability to thrive in a wide range of environmental conditions, where it can significantly modify ecosystems by altering soil characteristics, releasing allelopathic chemicals that may inhibit the growth of other plants, and forming dense thickets that reduce the space available and development chance of native vegetation. Ailanthus has been recognized as the most widespread and invasive alien tree species in Sicily (Italy), with a capillary presence over the entire regional territory, where it poses a serious threat to the biodiversity of the local Mediterranean ecosystems.

Ecohydrological models can simulate vegetation dynamics and predict Ailanthus encroachment mechanisms also in presence of disturbance effects and under climate change. In this work, the CATGraSS, an ecohydrological Cellular Automata model (Zhou et al., 2013), has been used for simulating spatio-temporal dynamics of Ailanthus altissima in a specific site of “Vallone di Piano della Corte” Nature Reserve, in the Erei mountains in central Sicily (Italy). The study area has a surface of approximately 1 km² and it is characterized by a relevant nucleus of Ailanthus that has been growing rapidly in recent years. The study aims to reconstruct Ailanthus altissima spatio-temporal evolution in the study area over the last century. The model has been calibrated using the current Ailanthus distribution maps, obtained by classifying high-quality satellite images, collected by PlanetScope constellation, exploiting modern remote sensing techniques, together with field surveys.

How to cite: Alongi, F., Badalamenti, E., Capodici, F., De Caro, D., Ciraolo, G., La Mantia, T., Pumo, D., and Noto, L. V.: Encroachment analysis of the invasive tree species Ailanthus altissima in Sicily (Italy) through an ecohydrological cellular automata model , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18767, https://doi.org/10.5194/egusphere-egu24-18767, 2024.

Urbanisation substantially alters the permeability of the land surface and modifies the vegetation cover extent and type. These landcover changes profoundly affect the hydrological and energy budget. While the role of urbanization on the local flood response has been extensively studied, its effect on the long-term hydrological budget is much less known as computing the latent heat flux (evapotranspiration) in urban areas is still challenging. However, knowledge on the urban hydrological budget is important as many cities are planning water sensitive urban designs and water harvesting could be key to support an increasing amount of urban vegetation.

This study quantifies how urbanization changed the long-term hydrological budget of the island city state Singapore for the period between 1982 to 2021. To do so, we use two state-of-the-art mechanistic models which include all the major hydrological components such as runoff, soil and interception water storage, transpiration, and evaporation. The first is Tethys-Chloris (T&C), which is a mechanistic ecohydrological model that can resolve the water, carbon and energy budgets at high spatio-temporal resolutions but considers the urban effects in a simplistic way by only modifying the impervious fraction of the land surface and its roughness. The second is its urban counterpart, Urban Tethys-Chloris (UT&C), which explicitly resolves shading and radiation reflection within an urban canyon accounting for different urban vegetation types and configurations and explicitly resolves the local urban climate and hydrology. UT&C is however too computationally costly to simulate an entire city at high spatial resolution. Hence, a machine learning approach, where a multimodal neural network comprising a Conv1D layer followed by LSTM layers for dynamic meteorological inputs and Dense layers for static inputs such as urban properties, is used to re-map UT&C outputs over the entire city based on a few selected covariates.

By cross comparing the different approaches to compute the long-term water budget over urban areas, we highlight the involved uncertainties, and we can gain insights into the impact of urban development on modifying the water availability in Singapore. The island city-state relies on water harvesting as one source of water supply for households and knowledge of water availability is extremely important for long-term water management purposes.

How to cite: Lin Xu, Y., Meili, N., and Fatichi, S.: Long-term hydrological budget over urban areas: approaches and challenges, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13909, https://doi.org/10.5194/egusphere-egu24-13909, 2024.

The underlying surface structure is being reshaped by climate change and human activities, which in turn affects the hydrological processes in inland river basins, with significant consequences for coupling patterns of water and land resources in inland river basins of arid and semi-arid regions. However, current studies of coupling pattern of water and land resources analysis focus on available water and visible land resources in the districts, so that there is an urgent need for research on the simulation and prediction for water and land resources coupling of the micro-scale. Therefore, this study firstly evaluated and predicted the land resources by MCE-CA-Markov model and soil quality index function with environment factors and socio-economic factors, then generalized and simulated the water resources by SWAT, and construct the Water-Land Nexus Model for water conservation and water consumption zones to clear the impact mechanisms of water and land resources nexus in inland river basins. The results show that the nexus index of water and land resources present a decreasing distribution from water conservation area to water consumption area of the Shiyang River Basin, with that being lower than 0.1 (mainly in the water consumption area). The coupling index of water and land resources of Shiyang River Basin decreases from 0.1105 in 1980 to 0.1071 in 2000. In 2020-2050, the water conservation area exhibit an increasing trend, but that of the water consumption area is decreasing. The Geo-detector results show that soil quality index, blue water resource and DEM are the main factors influencing the coupling of water and land resources in Shiyang River Basin, follow by precipitation, temperature and green water resource, and the effects of POP and GDP could be negligible. Furthermore, the interactions between natural and socio-economic factors are stronger than the ones within each other, indicating that natural factors are the main influences on water-land nexus and it is important to consider the interactions of nature along with the human activities.

How to cite: Zhu, M., Feng, Q., Liu, W., Zhang, C., and Zhang, J.: Patterns, controls and predictions of water and land resources nexus in a typical inland river basina: A green-blue water perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13181, https://doi.org/10.5194/egusphere-egu24-13181, 2024.

The rainfall erosivity influences the detachment of soil particles, movement and washing away the surface soil layers, which affects soil degradation and leads to various environmental problems. It depends primarily on the kinetic energy of raindrops, determined by the size and velocity of raindrops. However, rainfall microstructure (size, velocity and number of raindrops) is significantly changed during the process of rainfall interception. Precipitation, that is not intercepted by the vegetation, reaches the ground as throughfall (falling directly through the gaps in the canopy or dripping from the leaves and branches) or stemflow (flowing down the branches and stem). Therefore, the kinetic energy of throughfall under the vegetation is different than kinetic energy of open rainfall.

In the urban park located in Ljubljana, Slovenia, we have monitored the rainfall microstructure in the open and underneath the deciduous (Betula pendula Roth.) and coniferous (Pinus nigra Arnold) trees between 12 July 2022 and 19 July 2023. We have analysed the differences between rainfall microstructure and kinetic energy of raindrops in the open and underneath the trees.

The observed average number of raindrops per event under both trees was lower than the number of raindrops in the open. Also, the average kinetic energy of drops per event was significantly lower under the trees than in the open. Additionally, an analysis of factors influencing the kinetic energy of throughfall drops underneath the both trees was performed using the boosted regression trees and random forest models. Both models identified rainfall amount as the most influencing factor.

Acknowledgments: Results are part of the research programme P2-0180 and research projects J2-4489, N2-0313 and J6-4628, financed by the Slovenian Research Agency (ARIS).

How to cite: Zabret, K., Radulović, L., Alivio, M. B., Bezak, N., and Šraj, M.: Factors influencing the kinetic energy of throughfall drops, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8204, https://doi.org/10.5194/egusphere-egu24-8204, 2024.

The impacts of alternating dry and wet conditions on water production and carbon uptake at different scales remain unclear, which limits the integrated management of water and carbon. We quantified the response of runoff efficiency (RE) and plant water-use efficiency (PWUE) to a typical shift from dry to wet episode of 2003–2014 in Australia's Murray-Darling basin using good and specific data products for local application, including Australian Water Availability Project, Penman-Monteith-Leuning Evapotranspiration V2 product, MODIS MCD12Q1 V6 Land Cover Type and MODIS MOD17A3 V055 GPP product. The results show that there are significant power function relationships between RE and precipitation for basin and all ecosystems, while the PWUE had a negative quadratic correlation with precipitation and satisfied the significance levels of 0.05 for basin and the ecosystems except the grassland and cropland. The shrubs can achieve the best water production and carbon uptake under dry conditions, while the evergreen broadleaf trees and evergreen needleleaf trees can obtain the best water production and carbon uptake in wet conditions, respectively. These findings help integrated basin management for balancing water resource production and climate change mitigation.

How to cite: Lu, Z., Feng, Q., and Xie, J.: Basin management inspiration from impacts of alternating dry and wet conditions on water production and carbon uptake in arid region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13757, https://doi.org/10.5194/egusphere-egu24-13757, 2024.

Knowledge on relationship and determinants of water and carbon dioxide (CO2) exchange is crucial to land managers and policy makers especially for the desertified land restoration. However, it remains highly uncertain in terms of water use and carbon sequestration for artificial plantation in desert. Here, the continuous water and carbon fluxes were measured using eddy covariance (EC) in conjunction with hydrometeorological measurements over an artificial C4 shrub, Haloxylon ammodendron (C. A. Mey.) Bunge, from July 2020 to 2021 in Tengger Desert, China. In the entirely 2021, evapotranspiration (ET) was 189.5 mm, of which 85% (150 mm) occurred during growing season, that was comparable with precipitation (132.2 mm) plus dew (33.5 mm) and potential other sources (e.g. deep subsoil water). This ecosystem was a strong carbon sink with net ecosystem production (NEP) up to 446.4 g C m-2 yr-1, which was much higher than surrounding sites. Gross primary production (GPP, 598.7 g C m-2 yr-1) was comparable with other shrubs but ecosystem respiration (Re, 152.3 g C m-2 yr-1) was lower. Random Forest showed that environmental factors can explain 71.56% and 80.07% variation of GPP and ET, respectively. However, environmental factors have divergent effect on water and carbon exchange, of which soil hydrothermic factors (e. g. soil moisture content and soil temperature) determine the magnitude and seasonal pattern of ET and Re, while aerodynamics factors (e.g., net radiation, atmospheric temperature and wind speed) determine GPP and NEP. As such, divergent response of abiotic factors resulted in the decoupling of water and carbon exchange. Our results suggest that H. ammodendron was a suitable species for large-scale afforestation in desert or desertification-prone region given its low water use but high carbon sequestration. Therefore, we concluded that artificial planting H. ammodendron in dryland could provide an opportunity for climate change mitigation, however, the long-term time series data would be needed to confirm it.

How to cite: Yu, T., Han, T., Xi, H., and Li, B.: Relationship and determinants of water and carbon dioxide (CO2) exchange in desert ecosystem, China , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13561, https://doi.org/10.5194/egusphere-egu24-13561, 2024.

The effects of water on vegetation have always been a concern. It is an important support as well as a major limiting factor with respect to vegetation growth. By analyzing the spatiotemporal changes and correlations between precipitation (PRE), soil moisture (SM), vapor pressure deficit (VPD), and normalized difference vegetation index (NDVI) in the Yellow River Basin, we explored the different effects of different water elements on vegetation. Our findings reveal the following: (1) NDVI and the three water elements report an increasing trend in the Yellow River Basin, with NDVI increasing most significantly. (2) The changes in vegetation are closely related to arid and humid zoning of the Yellow River Basin. NDVI of arid regions is significantly lower than that of humid regions; additionally, NDVI of natural vegetation in arid regions is lower than that of crops planted in irrigation areas, whereas the opposite is true in humid regions. (3) 92.1% of the Yellow River Basin showed an increase in NDVI, and 76.4% showed a significant increase. The proportions with trends of increasing in PRE, SM, and VPD were 75.40%, 51.88%, and 49.71%, with significant increases of 4.5%, 9.5%, 17.9%, respectively; (4) Vegetation in the Yellow River Basin was most positively affected by PRE, followed by SM and VPD. PRE mainly affected the natural vegetation on both sides of the boundary between the arid and semi-arid regions and the semi-humid regions. SM mainly affected the natural vegetation in the arid and semi-arid regions, whereas VPD mainly affected the crops in the irrigation areas, and the irrigation areas in arid regions were affected the most. These findings contribute to a deeper understanding of the relationship between water elements and vegetation, as well as the formulation of strategies for the healthy development of regional natural vegetation and crops in areas of irrigation.

How to cite: Jin, X.: Different effects of Multiple Water Elements on Vegetation: A Case Study of the Yellow River Basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4624, https://doi.org/10.5194/egusphere-egu24-4624, 2024.

Artemisia ordosica can prevent desertification and increase carbon sequestration, and it has been extensively planted in the Mu Us Desert, China. Evapotranspiration (ET) plays an important role in the survival of Artemisia ordosica. However, the controlling factors of ET remain unknown. To investigate the influencing factors on the actual evapotranspiration, we set up a weighing lysimeter with Artemisia ordosica in the Mu Us Desert. We collected data of air temperature (Ta), net radiation (Rn), wind speed (WS), soil moisture (θ), vapor pressure deficit (VPD), and heat flux (HF). The multiple linear regression model was used to quantify the influence of the six environmental factors on the ET. In addition, we applied the boosted regression tree (BRT) method to quantify the relative contribution of these environmental factors to ET. Our results show that annual ET was 444.46 mm, which was mainly influenced by the VPD during the dry season and Rn during the rainy season. This is different from the previous results which emphasized the importance of θ and Ta. The BRT results show that VPD and Rn are the most contributors to ET in the research area. In addition, ET significantly decreased when the soil moisture was less than 0.063 cm³/cm³. ET can increase by an average of 90% after a rainfall event. Our results have significance for the hydrological cycle and ecological environment protection.

How to cite: Zhang, Z., Feng, Q., Gong, C., Zhu, M., Liu, W., Zhang, J., and Li, A.: The influence of environmental factors on the actual evapotranspiration of Artemisia ordosica , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16875, https://doi.org/10.5194/egusphere-egu24-16875, 2024.

The Yellow River basin (YRB), as a crucial ecological corridor in the northern part of China, has experienced profound changes in multiple eco-hydrological processes. However, there is still lack of a global view on the variations and causal interactions in the complex hydro-ecological system of YRB. In this study, a set of eco-hydrological variables, regarding water resources (surface water, soil water, groundwater) and ecological environment (vegetation growth, productivity, water use efficiency) are used to represent the main characteristics of the eco-hydrological system in different sub-regions of YRB. The objective of this study is three-fold. Firstly, the individual variation of each eco-hydrological variable was unraveled using trend analysis. Secondly, network analysis was used to analyze the synergistic variations among variables. Finally, an advanced causal discovery tool incorporating prior knowledge was used to investigate the potential causal interactions in eco-hydrological system. The results indicate the decrease of terrestrial water storage anomalies (TWSA) in most parts of the YRB, which is mostly due to the substantial depletions in ground water. The vegetation growth and productivity have noticed prominent increasing trends in YRB, and such increase in the source region is largely due to the warmer climate condition and in the middle reaches is mainly because of the large-scale vegetation restoration. However, the ecosystem water use efficiency (WUE) is not very optimistic, especially in the source region. The causal discovery method captures the inhibitory effect of evapotranspiration on WUE in the upper and some parts of the middle reaches of YRB. Our study provides a new perspective to recognize the complicated eco-hydrological conditions and their variations in YRB during 2001-2019, as well as the potential mechanisms driving these variations.

How to cite: Xu, Y., Wang, L., Gu, H., and Liu, L.: Variations and causal interactions in the eco-hydrological system of Yellow River basin, China: A Network Perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19628, https://doi.org/10.5194/egusphere-egu24-19628, 2024.

Ecosystem water use efficiency (WUE, defined as the ratio of primary productivity to evapotranspiration) has garnered significant attention in recent years for its role as a vital indicator of the interplay between carbon and water cycles. Numerous studies have underscored the substantial impact of elevated CO₂ concentrations on WUE through changes in climate and land surface properties. However, the relative contributions of these factors and their interrelations remain less clear. This study delves into the linkage between WUE and the water-energy exchange dynamics within the Yellow River Basin, employing the Budyko framework model as a foundation. We propose and validate a linear Budyko model tailored to WUE, demonstrating satisfactory physical performance (R² = 0.60-0.73). Building on this, we construct an attribution framework for WUE, grounded in the Budyko model and global climate models (GCMs), to quantitatively disentangle the impacts of climate and land use change, as well as to elucidate the mechanisms underlying CO₂-induced radiative and biogeochemical effects on WUE. Our attribution analysis suggests that the WUE of the Yellow River Basin is anticipated to increase by 0.36-0.84 (g C/kg H₂O) in future scenarios, with climate change being the predominant driving force (77.9%-101.4%). The study also uncovers variations in the response of WUE to different drought conditions within the basin. Specifically, we observe an increase in WUE under moderate drought conditions, whereas a decline is noted in most areas as drought severity escalates. Under high emissions scenarios, WUE exhibits a more pronounced sensitivity to drought, particularly under extreme conditions. The outcomes of this research contribute to our understanding of how future CO₂ concentration increments, under varying scenarios, may induce changes in WUE in the Yellow River Basin. Moreover, they reveal the prospective response mechanisms of vegetation to drought events within the basin, offering a scientific basis for the formulation of regional ecological strategies and water management practices.

How to cite: Chen, S., Xu, Y., and Guo, Y.: Attribution and Response of Water Use Efficiency to Future Changes  in the Yellow River Basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19281, https://doi.org/10.5194/egusphere-egu24-19281, 2024.

Central Europe has experienced an extreme drought over the last five summers, which has led to a deficit in precipitation and discharge unlikely to be replenished quickly. Due to climate change, extreme weather events and accompanying droughts are likely to occur more frequently in the future putting pressure on aquatic ecosystems. In addition, rivers have been significantly modified over the years, with channelization and the construction of dams drastically altering the natural flow of the river. Floodplains have been cut off and natural habitats have been lost. This underlines the need to investigate the interactions of climate change and antropogenic alterations to rivers and to establish a safe operating space for floodplain areas to ensure their ecological function. To achieve this, we investigated 36 floodplain lakes near the Elbe River in Magdeburg, Germany, with varying connectivity to the main river and different characteristics of each lake. Water samples were taken from the lakes, the main river and the groundwater. Major ions and isotopes to determine the origin of the water. Further, chlorophyll a was sampled and parameters such as oxygen and hydrogen sulfide were taken. Along with recorded fish kills and measured water level, a scoring system was established to determine the degree of impairment and habitat loss of each lake. Connectivity, defined here as the frequency of an existing surface connection of the lake to the main river, was determined to provide a measure of the impact of anthropogenic modification and channelization of the river bed. The difference in deuterium excess between fall and spring served as a measure of evaporation and thus of the influence of climate change during the sampling campaign. Critical chlorophyll a concentrations were measured in surface waters in lakes with less than 50 % connectivity, critical oxygen concentrations in lakes with less than 10 % connectivity. Fish kills, hydrogen sulfide, siltation and dry-out occurred predominantly in lakes with a low connectivity. Finally, lakes with a small perimeter by area were found to exhibit fewer signs of degradation and habitat loss. Our results suggest that lakes that are connected to the main river are better able to respond to drought stress caused by climate change. Therefore, better connectivity to the main river may help to reduce habitat degradation or loss in the floodplain ecosystem.

How to cite: Coder, L., Büttner, O., Knöller, K., Kronsbein, P. M., Musollf, A., and Tittel, J.: How anthropogenic modification of riverscapes reduce the resilience of floodplain waters to drought, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19734, https://doi.org/10.5194/egusphere-egu24-19734, 2024.

The purpose of this work is to present the results of a literature data re-analysis of HSI and demonstrate the existence of a universal level of similarity in the ranges of hydraulic variables for the considered species.

The decline in biodiversity within freshwater ecosystems is a critical issue influenced by many factors, including the increasing pollution levels and the proliferation of invasive species. Globally, river management strategies have increasingly incorporated river restoration efforts and actions aimed at preserving freshwater species, such as the brown trout (Salmo trutta L.). From a quantitative point of view, the efficiency of proposed restoration measures on river ecomorphology is assessed via the HSI, whose use is widely embraced by aquatic ecologists, river scientists, and engineers. For the specific case of the brown trout, the HSI takes into account several environmental factors, including flow velocity, water depth, and substrate type, which directly represent the environmental characteristics of the habitat. Despite variations in HSI curves based on geographical location and other incidental factors, a notable degree of similarity and shared dependence on flow discharge is observed among data in the literature. This prompts a crucial question about the extent of similarity in these curves for a particular species concerning ecohydraulic variables.

This work aims to address this query by considering literature data of HSIs measured in different worldwide locations and by various authors, all focused on the same fish species (i.e., the brown trout). The dependence of the HSI on particular ecohydraulic variables, such as water depth, velocity, temperature, and substrate are analysed by attributing the range of optimal values to the recommendations of the related authors. Histograms indicating the level of goodness of each range are then built and eventually smoothed by using fitting functions to reveal the universal characteristics of HSIs among worldwide rivers for the species being considered.  

How to cite: Padoan, F., Calvani, G., de Cesare, G., and Perona, P.: Assessing the Universality of Habitat Suitability Indexes (HSI) for brown trout (Salmo trutta L.) in Relation to Ecohydraulic Variables, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18264, https://doi.org/10.5194/egusphere-egu24-18264, 2024.

Quantifying the effects of external climatic and anthropogenic stressors on aquatic ecosystems is an important task for scientific and management progress in the field of water resources. In this study, we propose an innovative use of biotic communities as real-time indicators, which offers a promising solution for directly quantifying the impact of these external stressors on aquatic ecosystems. Specifically, we investigated the influence of natural river floods on biotic communities using freshwater mussels (FMs) as reliable bioindicators. Using a well-established valvometry technique, we measured the valve-opening behaviour of FMs, considering both amplitude and frequency. The valve gap movement of the FMs was monitored by installing a magnet on one valve and a Hall effect sensor on the other valve and recording the magnetic field between the magnet and the sensor itself using an Arduino board, which changes according to the distance between the two valves. The recorded data was then analysed using the Continuous Wavelet Transform (CWT) analysis to study the time-dependent frequency of the signals. The experiments were carried out in a laboratory flume and in the River Paglia (Italy). The laboratory experiments were carried out with FMs in two configurations: freely moving or immobilised on vertical bars. The immobilised configuration was necessary for the field application to prevent the FRMs from packing against the downstream wall of the protection cage during floods. These experiments allowed us to verify that immobilised mussels show similar responses to abrupt increases in flow conditions as free mussels, but produce more consistent and interpretable signals than free mussels due to the reduced number of features resulting from movement constraints. We then analysed the response of thirteen immobilised mussels in real river conditions during a moderate flood on 31 March 2022.  The FMs in the field showed a rapid and significant change in valve gap frequency as the flood escalated, confirming the laboratory results. These results highlight the effectiveness of using FMs as bioindicators for assessing flood impacts on aquatic ecosystems, and emphasise the utility of CWT as a powerful signal processing tool for analysing valvometric time series. The study proposes the integration of FM valvometry and CWT for the development of operational real-time Biological Early Warning Systems (BEWS) aimed to monitor and protect aquatic ecosystems.

How to cite: Piccolroaz, S., Pilbala, A., Riccardi, N., Benistati, N., Modesto, V., Termini, D., Manca, D., Benigni, A., Corradini, C., Lazzarin, T., Moramarco, T., and Fraccarollo, L.: Using freshwater mussel valvometry data as a real-time biological warning system for aquatic ecosystems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16608, https://doi.org/10.5194/egusphere-egu24-16608, 2024.

Overexploitation of water resources has led to severe ecological degradation and even desertification in many terminal wetlands in arid inland river basins, northwestern China. To restore the degraded vegetation ecosystem, ecological water conveyance projects (EWCPs) have become an important measure. Scientific assessment of the ecological stability of restored vegetation is of great importance for formulating reasonable ecological water management. Considering this, a systematic study was conducted in a typical terminal wetland of the Qingtu Lake Wetland (QLW) in Shiyang River Basin, northwestern China. The pixel-scale restored vegetation area (RVA) each year since the start of EWCP was extracted based on remotely sensed vegetation index. RVA increased dramatically in the first five years and became stable from 2016. The time lag of the response of RVA increase to ecological water conveyance was about 2 years. A bell-shaped function between RVA and groundwater depth was obtained based on the micro terrain of QLW via UAV. Five groundwater depth thresholds were then determined. The optimal groundwater depth in the hydrometric station was 2.91±0.09 m for the maximal RVA (17.08±3.25 km²). The optimal ecological water volume into Qingtu Lake was further estimated (the volume is 2224.4×10⁴ m³) for the maximal RVA by a polynomial function between ecological water volume and groundwater depth. With the help of remotely sensed soil salinization and water surface, the vegetation restored during the first few years of EWCP in the southwest, west and north of QLW was found to degrade again due to the aggravation of soil salinization in these regions since 2019. Soil salinization was accelerated by the low groundwater depth with high mineralization and high evaporation capacity of climate without adequate inundation of ecological water by the unreasonable water allocation strategy. Under current simple and lax ecological water management in QLW, soil salinization will intensify and vegetation will further degrade. In other words, the ecological status of restored vegetation in QLW is unstable. Based on the optimal ecological water volume, even distribution of ecological water is helpful to maintain the stability of restored vegetation.

How to cite: Hu, S. and Zhao, Q.: The ecological stability of restored vegetation by ecological water conveyance project in a typical terminal wetland in an arid inland river basin, northwestern China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15124, https://doi.org/10.5194/egusphere-egu24-15124, 2024.

The escalating levels of uranium in groundwater present a critical challenge to public health and environmental sustainability in the Malwa region of Punjab, India. This study addresses the dearth of understanding regarding uranium contamination by investigating its hydrogeochemical behavior in the hot, sub-tropical steppe, semi-arid Malwa region. Our research aims to unravel the controlling factors influencing uranium mobility and distribution in groundwater. Ion chromatography was employed for the comprehensive determination of cations (Na⁺, K⁺, Li⁺, Ba⁺) and anions (F^-, Cl^-, Br^-, NO3-, SO₄^2-, PO₄^-). Inductive-coupled plasma mass spectrometry was utilized for the quantification of heavy elements including strontium (Sr), cadmium (Cd), lead (Pb), uranium (U), aluminium (Al), chromium (Cr), manganese (Mn), iron (Fe), copper (Cu), cobalt (Co), zinc (Zn), arsenic (As), and selenium (Se) concentrations in groundwater samples. Results indicate alarming uranium levels ranging from 1.13 to 299.40 µg/L with mean of 54.03 µg/L. 73% to 92% of samples surpassing Bureau of Indian Standards (BIS) and World Health Organization (WHO) guidelines. Groundwater is primarily of Mg-HCO3 type which exhibited alkaline characteristics attributed to silicate weathering, ion exchange, and carbonate weathering in semi-arid conditions. Cluster analysis grouped uranium with nitrate, sodium and potassium, emphasizing their interconnected behavior. Spearman correlation analysis revealed a close association between uranium concentrations and various parameters including electrical conductivity, total dissolved solids (TDS), alkalinity, nitrate, sulfate, Na, and K. TDS, nitrate, and alkalinity exhibited high correlations with uranium which indicates that salt-induced competition among ions is the primary cause of uranium mobilization. This is evident in increased uranium levels with mixed water species (Mg-Cl, Na-HCO3). Furthermore, concerning levels of arsenic and selenium exceeding BIS and WHO limits underscore additional health concerns. This research underscores the urgent need for understanding and managing uranium contamination in the Malwa region. The broader implications for public health and environmental sustainability necessitate immediate attention and comprehensive remediation strategies.

How to cite: Chauhan, N., Krause, S., Singh, J., Toor, A. P., and Srivastava, A.: Assessing the Mitigation of Uranium and Heavy Toxic Elements with Physicochemical and Hydrogeochemical properties of groundwater in the Malwa Region of Punjab, India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8990, https://doi.org/10.5194/egusphere-egu24-8990, 2024.

Wetlands, among the world’s most biodiverse and productive ecosystems, face severe threats from flow regime alterations, unsustainable water management, land-use conversion, increasingly exacerbated by climate change. Reduced connectivity between river channels and their floodplain habitats is often a consequence of subsequent drying, significantly degrading ecological health. We investigated the impacts of a century of river regulation and upstream water abstractions on the Lowbidgee Floodplain in semi-arid Australia - a nationally important wetland ecosystem on the lower Murrumbidgee River within the Murray-Darling Basin. This floodplain, which includes the indigenous-managed Gayini Wetlands and Yanga National Park, has a rich Aboriginal cultural heritage and supports a range of threatened and endangered native Australian species. We utilized Landsat and Sentinel satellite data to map wetland inundation patterns from 1988 to the present. Through the analysis of discharge data from the floodplain’s river gauges, we modelled the extent and frequency of wetland inundation under variable water availability scenarios, resulting from river regulation and climate change. Additionally, we evaluated the effects of altered flow and flood regimes on the health of flood-dependent vegetation, using remote sensing-derived vegetation indices such as the NDVI and Fractional Vegetation Cover (FVC). Our study aims to inform environmental flow management for large-scale river and wetland restoration efforts. It also provides the indigenous landowners, the Nari Nari Tribal Council, with crucial data to support their land and water management.

How to cite: Kreibich, J., Bino, G., Glamore, W., and Kingsford, R.: Satellite-Based Inundation Modelling for Large-Scale Wetland Restoration in Semi-Arid Australia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4869, https://doi.org/10.5194/egusphere-egu24-4869, 2024.